Antenna for miniature radio receiver including portions of receiver housing and chassis

ABSTRACT

Antenna for radio receiver of the capacitively loaded vertical ground plane type wherein an active vertical portion is formed by parts of the receiver and is connected to a conductive escutcheon to form a capacitive loading structure for the vertical antenna. The lower end of the vertical antenna is connected to shield cans and grounded conductors on the chassis which form an effective ground plane. The signal from the top of the vertical antenna is coupled through a matching circuit to the base of a transistor. A jack for connecting an external antenna is connected between the ground plane and a point on the vertical antenna.

United States Patent Inventors Joseph F. Cramer, Jr.

Downers Grove, 11].; Thomas M. Yackish, Hammond, Ind. Appl. No. 744,837Filed July 15, 1968 Patented Apr. 6, 1971 Assignee Motorola, Inc.

Franklin Park, III. a corporation of Illinois ANTENNA FOR MINIATURERADIO RECEIVER INCLUDING PORTIONS OF RECEIVER HOUSING AND CHASSIS 10Claims, 4 Drawing Figs.

[56] References Cited UNITED STATES PATENTS 2,840,694 6/1958 Morgan343/702 3,307,108 2/1967 Induni 325/119 Primary Examiner-Robert L.Griffin Assistant Examiner-Anthony H. Handal Attorney-Mueller andAichele ABSTRACT: Antenna for radio receiver of the capacitively loadedvertical ground plane type wherein an active vertical portion is formedby parts of the receiver and is connected to a conductive escutcheon toform a capacitive loading structure for the vertical antenna. The lowerend of the vertical antenna U.S. Cl 325/361, is connec ed to shield cansand grounded conductors on the 343 /7()2 chassis which form an effectiveground plane. The signal from Int. Cl 1104b 1/18, h p f h ver i l ntennais coupled through a matching H041 1/08 circuit to the base of atransistor. A jack for connecting an ex- Field of Search 343/702; ternalantenna is connected between the ground plane and a 325/1 19, 354, 365,361 point on the vertical antenna.

E/2l 2G Tl n l ll 27...? u 28 4 l7 'f' H g 2 Patentd April 6, 1971 IFIG. 3

I O S 2 2 m n W. mad? u mwmu 3 5/; u J //J I /J m 2 a 20 Z 3 2 nun-mmJOSEPH F CRAMER JR. THOMAS M. YACKISH. BY W. M1941) ATTYS.

ANTENNA FOR MINIATURE RADIO RECEIVER INCLUDING PORTIONS OF RECEIVERHOUSING AND CHASSIS BACKGROUND OF THE INVENTION subject to breaking. Insome miniature radio units an antenna has been provided in a cordextending from the unit, such as a cord connecting a microphone to atransmitter, or an earpiece to a receiver. However, in many cases such aprojecting cord is not needed or desired, and this arrangement cannottherefore be used.

SUMMARY or 'Il-IEINVENTION,

It is an object of the present invention to provide an antenna for aradio device which is formed as anintegral part of the housing andchassis of the device.

Another object of the invention is to provide an antenna for anultrahigh frequency radio receiver which is entirely selt contained andhas no protruding parts.

A further object of the invention is to provide an antenna for aminiature radio receiver by providing cooperation between parts havingother functions in the receiver so that the cost of the antenna is aminimum.

The antenna of the invention is formed by a conductive escutcheon plateof the housing of the radio unit, a conductive bracket for jackconnectors, and parts of the chassis of the unit including shield cans.The antenna acts as a capacitively loaded vertical antenna with thevertical section being formed by a portion of the bracket, conductingmaterial on the chassis and a strap connected to a shield can. Thecapacitive loading structure is formed by part of the bracket and theescutcheon plate which includes a finger engaging the bracket. Theground plane is formed by the shield cans and the ground conductors onthe chassis. When used in a receiver, signal is derived from the top ofthe vertical antenna section by a connection from the bracket through amatching network to the base of a transistor. The transistor is providedin one of the shield cans and has its collector connected to a coiltherein which is coupled to other coils which provide the radiofrequency selectivity for the receiver.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION OF THE EMBODIMENTILLUSTRATED In FIG. I there is shown the portable receiver which may bea paging receiver to be carried by a person so that he can receivemessages. Such a paging receiver can be used over a limited area, suchas in a city, or within a building or complex of buildings. The receiverhas an insulating housing including a louvered section I] behind which aloud speaker 17 (FIG. 3)

is mounted for producing tone and/or voice signals. At the top of thehousing is a metal escutcheon plate 12 which has a first right angleportion extending across the top of the receiver and a second portionextending downwardly to the top of the louvered section 11. Jacks l3 and14 are provided at the top of the receiver for connection of an externalantenna and an external earpiece, respectively. The escutcheon plate 12has openings through which the jacks extend. A thumb operated control 15operates a switch to turn on the receiver and also a volume control tocontrol the level of the sound reproduced. A second push operated switch16 may be used to provide a further operation. In some paging receiversa signalling tone is first received and the switch button 16 must bepressed and held to hear a voice message. In other units the voicemessage is heard automatically following the tones, and the switchbutton 16 may be used to reset the receiver for response to another tonecode.

FIG. 2 shows portions of the receiver with the housing not shown. Theconducting escutcheon plate 12 is shown and this includes an integralupwardly turned finger 20 which is engaged by the edge of a conductingbracket 22 which supports the jacks l3 and 14. The bracket 22 is rivetedto the chassis 24, which may be formed by an insulating printed circuitboard, by conducting rivets 25. The chassis 24 has conducting coatings26 and 27 on the rear thereof, with the coating 27 including electricalground connections between various parts mounted on the chassis. Some ofthese parts are provided in the conducting shield cans 28 and 29 whichextend from the top side of the chassis 24. A conducting strap 30 iselectrically connected to the coating 26, which is in turn connectedtothe bracket 22 by rivets 25. The strap 30 has an angle portionelectrically connected to the shield can 28.

The vertical portion of the bracket 22 together with the conductingcoating 26 on the backside of the chassis and the vertical portion ofthe strap 30 form a vertical antenna. The conducting rivets 25electrically connect the bracket 22 to the coating 26 and the strap 30is soldered to the coating 26. The bottom end of the vertical antenna isconnected to the ground plane formed by the shield cans 28 and 29 andalso by the conducting coating 27 which extends on the insulatingchassis 24 below the shield cans. These conducting portions form aneffective ground plane for the antenna. The horizontal top portion ofthe bracket 22 in cooperation with the metal escutcheon 12 and theconnecting finger 20 form a capacitor which loads the upper end of thevertical antenna. As shown in FIG. 3, a resilient pad 21 is providedback of the finger 20 to apply pressure thereto so that the finger 20presses against the edge of the bracket 22. When the chassis is placedwithin the housing, the edge of the bracket wipes against the finger 20.This provides a good electrical connection between the bracket and theescutcheon.

FIGS. 3 and 4 show the electrical connections from the antenna to thereceiver. Connection is made from the upper horizontal portion of thebracket 22 through the coil 32 and variable capacitor 34 to the base oftransistor 35. The coil and capacitor are shown physically in FIG. 3 anda schematic diagram of these elements and the transistor is shown inFIG. 4. As indicated by FIG. 4, the transistor 35 is in the shield can28 along with the coil 36 connected to the collector of transistor 35.The emitter of transistor 35 is connected to ground through the chassis.Coil 36 is part of a tuned output circuit including capacitor 37 andcapacitor 38. Capacitor 38 isolates the coil 36 from ground for directcurrent so that the bias potential for the collector of transistor 35can be applied through this coil. The bias potential is applied atterminal 40 which is bypassed by capacitor 41. The potential is appliedthrough a voltage divider including resistors 42, 43 and 44, with thevoltage across resistor 44 being applied to the base electrode oftransistor 35, and the voltage across resistors 43 and 44 being appliedthrough coils 45 and 36 to the collector electrode. Capacitor 47 andresistor 48 provide feedback from the tuned output circuit to the baseelectrode. The coil 36 of the tuned circuit may be coupled to othertuned circuits to provide the radio frequency selectivity of thereceiver.

As shown in FIG. 4, the jack for receiving a plug connected to anexternal antenna has a connector 50 connected to the shield can 28(ground) and a connector 51 connected to the rivet 25. The input fromthe external antenna is therefore connected to a tap on the verticalantenna element to match the impedance of the external antenna to theantenna formed by the receiver components.

The receiver circuit may include a selective calling system whichresponds to a code including particular frequencies. These frequenciesare selected by reed devices 55 (FIG. 2).

The receiver as illustrated in HO. 1 of the drawing, has the followingdimensions; 2%inches wide, 5% inches high and 1 H16 inches thick. Theweight of the receiver including a battery which is positioned at thebottom of the housing is between 11 and 12 ounces, depending on theparticular battery used. The escutcheon is approximately 2% inches longwith the top portion having a width of about three-fourths of an inchand the front portion having a width of about one-half of an inch. Thelength of the active vertical antenna element is approximatelythree-eights of an inch.

The antenna as described has been found to be highly effective to pickup signals under various difierent operating conditions. Since it isfonned by parts having other functions in the receiver, it is providedat very low cost.

We claim:

1. An antenna for a miniature radio device having an insulating housingwith a part thereon formed of conductive material, and having a chassiswithin the housing with conducting means at a reference potential, suchantenna including conductor means extending vertically within thehousing when the radio device is in the position of use to form anactive antenna element, first conductive means connecting the upper endof said conductor means to the conductive part of the housing andforming therewith a capacitor for loading said antenna element, andsecond conductive means connecting the lower end of said conductor meansto the conducting means of the chassis to form an effective ground planefor said antenna element.

2. The antenna of claim 1 wherein said conductor means is formed of aplurality of parts, at least one of which has a further function in theradio device.

3. The antenna of claim 1 including conducting shield cans on thechassis which form at least a part of the ground plane for said antennaelement.

4. A miniature radio receiver including in combination, an insulatinghousing having an escutcheon thereon formed of conductive material,-achassis within the housing with conducting means at a referencepotential, conductor means on said chassis extending vertically withinthe housing when the receiver is in the position of use to form anactive antenna element, first conductive means connecting the upper endof said conductor means to said escutcheon and forming therewith acapacitor for loading said antenna element, and second conductive meansconnecting the lower end of said conductor means to said conductingmeans of said chassis to form an effective ground plane for said antennaelement.

5. The structure of claim 4 including a conductive bracket which forms apart of said conductor means and which has a portion in electricalconnection with said escutcheon.

6. The structure of claim5 wherein said bracket supports a jack forconnecting an external antenna to the receiver, and said jack has afirst connector connected to said conductor means and a second connectorconnected to said second conductive means.

7. The structure of claim 4 wherein said escutcheon includes aconductive finger, and wherein said conductor means and said firstconductive means are formed in part by a conductive bracket having aportion engaging said conductive finger.

8. The structure of claim 4 including a transistor forming the firststage of the receiver, and a matching circuit connected from said firstconductive means to said transistor for applying signals thereto.

9. The structure of claim 8 wherein said transistor has base, emitterand collector electrodes and said matching circuit is connected to saidbase electrode, and includin means connecting said emitter electrode tosaid secon conductive

1. An antenna for a miniature radio device having an insulating housingwith a part thereon formed of conductive material, and having a chassiswithin the housing with conducting means at a reference potential, suchantenna including conductor means extending vertically within thehousing when the radio device is in the position of use to form anactive antenna element, first conductive means connecting the upper endof said conductor means to the conductive part of the housing andforming therewith a capacitor for loading said antenna element, andsecond conductive means connecting the lower end of said conductor meansto the conducting means of the chassis to form an effective ground planefor said antenna element.
 2. The antenna of claim 1 wherein saidconductor means is formed of a plurality of parts, at least one of whichhas a further function in the radio device.
 3. The antenna of claim 1including conducting shield cans on the chassis which form at least apart of the ground plane for said antenna element.
 4. A miniature radioreceiver including in combination, an insulating housing having anescutcheon thereon formed of conductive material, a chassis within thehousing with conducting means at a reference potential, conductor meanson said chassis extending vertically within the housing when thereceiver is in the position of use to form an active antenna element,first conductive means connecting the upper end of said conductor meansto said escutcheon and forming therewith a capacitor for loading saidantenna element, anD second conductive means connecting the lower end ofsaid conductor means to said conducting means of said chassis to form aneffective ground plane for said antenna element.
 5. The structure ofclaim 4 including a conductive bracket which forms a part of saidconductor means and which has a portion in electrical connection withsaid escutcheon.
 6. The structure of claim 5 wherein said bracketsupports a jack for connecting an external antenna to the receiver, andsaid jack has a first connector connected to said conductor means and asecond connector connected to said second conductive means.
 7. Thestructure of claim 4 wherein said escutcheon includes a conductivefinger, and wherein said conductor means and said first conductive meansare formed in part by a conductive bracket having a portion engagingsaid conductive finger.
 8. The structure of claim 4 including atransistor forming the first stage of the receiver, and a matchingcircuit connected from said first conductive means to said transistorfor applying signals thereto.
 9. The structure of claim 8 wherein saidtransistor has base, emitter and collector electrodes and said matchingcircuit is connected to said base electrode, and including meansconnecting said emitter electrode to said second conductive means, andtuned circuit means connected between said collector electrode and saidsecond conductive means.
 10. The structure of claim 9 includingconductive shield cans on said chassis which form at least a part of theground plane, and wherein said transistor and said tuned circuit meansare provided in one of said shield cans.